The use of external structurants for providing rheological benefits to fluid detergent compositions is known. Examples of desired benefits include particle suspension, shear thinning properties, a thick appearance on the shelf, as well as stabilization of materials which are desired to be incorporated within the composition. See e.g. U.S. Pat. No. 6,855,680 to Smerznak et al. and U.S. Patent Appl. Nos. 2005/203213 to Pommiers et al.
Known external structurants include those such as those derived from castor oil, a fatty acid, fatty ester, or fatty soap water-insoluble waxes. These external structurants have been reported to be useful at levels up to 10% by weight. However, formulating these structurants requires making water-rich premixes and further, the structurant in the premix requires emulsification, making for a complex manufacturing process. In view of the current trend to concentrated detergent compositions, it would be desirable to identify a structurant, and a process, which do not introduce appreciable quantities of water into a detergent composition. Moreover, many structurants are susceptible to degradation by conventional detergent ingredients, such as by hydrolysis, or by enzyme breakdown. Of the structurants which are capable of withstanding such degradation, many do not provide sufficient rheological benefits at low levels, such as below 1 wt %. As such, there is an ongoing need for an external structurant which is not subject to such degradation, but capable of providing the desired rheological benefits at low levels.
Additional problems encountered with many known structurants is that a certain amount of water that must be incorporated with such structurants in raw material form, increasing transportation cost and processing complexities; difficulties forming liquid having the properties of gel, such as a shear thinning gel, a gel capable of suspending particles, and/or a thixotropic gel. In certain instances thixotropic gels may be desired for localized delivery of a liquid detergent composition. Another problem encountered with known structurants is obtaining the desired rheological properties in a liquid while using relatively low amounts of structurant.